Ribbon feed

ABSTRACT

Pivotally mounted plastic ribbon deck for an electronic business machine printer rotatably supporting two spools to normally present an operable position of ribbon in a lower inoperative position and liftable to move the ribbon to first or second upper operative positions by a rotatable plastic cam and a plastic lifting link, the latter being selectively moveable laterally to be engaged by different portions of the cam. Automatically reversible ribbon feed comprising a plastic feed pawl beam slidable on the ribbon deck and having one of two edge notches held by springs in engagement with a laterally oscillatable drive stud and one or the other of its pawl ends engaging a ribbon spool ratchet. When sliding of beam is prevented by ribbon resistance due to unwinding of all of ribbon from one spool to which its end is secured, the drive stud moves relative to the beam into engagement with the other edge notch and the springs tilt the beam to engage its other pawl end with the ratchet of the other spool to reverse the direction of the ribbon feeding.

United States Patent 1191 Hebron Apr. 29, 1975 l l RIBBON FEED l75l Inventor: Terrance J. Hebron, Arlington (57] ABSTRACT Hughts Pivotally mounted plastic ribbon deck for an elecl73] Assignee: Victor Comptometer Corporation. tronic business machine printer rotatably supporting Chicago, Ill. two spools to normally present an operable position of {22] Filed: Sept. 17, 973 ribbon in a lower inoperative position and liftahle to move the ribbon to first or second upper operative pol2l] Appl. No.: 397,883 sitions by a rotatable plastic cam and a plastic lifting link. the latter being selectively moveable laterally to 1521 us. c1 197/157; l97/l62 engaged l f pmions of f Cam l5 1 1 Int Cl H 33/56 ically reversible ribbon feed comprising a plastic feed 581 Field of Search H I97H6465 pawl beam slidable on the ribbon deck and having one of two edge notches held by sprmgs in engagement References Cied with a laterally oscillatable drive stud and one or the other of its pawl ends engaging a ribbon spool ratchet. UNITED STATES PATENTS When sliding of beam is prevented by ribbon resis- 2.859.352 11/1958 Suif l97/l5l X lance due [Q unwinding of all of ribbgn from one spool fi s? i to which its end is secured, the drive stud moves rela M1555 We s.;.f....i;.....-... 1971157 beam P @Pgagemem edge 3.513.957 5/1970 Ricciardi et 1. 197/151 and the spr'ngs the beam to engge Primary [summer-Stephen C. Pellegrino Attorney, Agent, or FirmMcCaleb. Lucas & Brugman pawl end with the ratchet of the other spool to reverse the direction of the ribbon feeding.

13 Claims, 6 Drawing Figures 65 53 H I 9 1 55 6Q 21 I 67 11 \72 71 1 l :51 11 u M/ "H111 PATENTEUAPR29I9?5 v1.880.271

saw 1 or 2 mason FEED BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to priming business machines, and more particularly to ribbon feeding and vibrating or lifting mechanism operable in response to electric signals.

2. Description of the Prior Art It has been customary in business machines having a ribbon, which is carried by laterally spaced spools with an operable portion extending from one spool to the other in a printing zone and between the printing members and the paper backed by a platen. to employ vibrating or lifting mechanisms for moving that operable portion of the ribbon vertically between a lower inoperative position and one or two upper operative positions to present differently colored portions of the ribbon in horizontal alignment with the printing members. Ribbon feed mechanisms also are known for advancing the ribbon in either direction through the printing zone. For example. US Pat. No. 654,18l discloses an auxiliary ribbon spool guide frame slidably mounted on shafts on which double spools are keyed for carrying differently colored ribbons in a blind printer. with one ribbon normally in an active printing position, and total taking mechanism operable to slide the auxiliary frame to shift the spools to move the other ribbon into active printing position. In that machine. the ribbon feed, which includes a number of parts, is mounted on a stationary machine frame that journals the ribbon spool shafts and drives one or the other of two ratchet wheels secured, respectively. to those shafts. Such mechanism is expensive and would be required to be even more complicated if an attempt were made to adapt it for normal positioning of both ribbons in inoperative positionv With all known lifting mechanisms which engage the edges of the ribbon in moving it vertically relative to the spools. curling, folding or tearing of the ribbon frequently results if the feeding thereof takes place when the ribbon is in either an upper or lower position, U.S. Pat. No. 2,692,556 recognizes this problem and offers a solution. in a machine employing an oscillating main drive shaft, which requires a complicated double train of linkages for actuating the usual ribbon lift guides and retaining them for a middle portion of each forward and rearward movement of the oscillatable drive shaft to maintain the operable portion of the ribbon in vertical alignment with the spools, together with manually reversible ribbon feed pawl operable only during such middle portions of the drive shaft oscillations.

SUMMARY OF THE INVENTION The present invention comprises a simple and inexpensive solution to the problems of avoiding edge wear and destruction of a ribbon in a business machine printer while moving the ribbon vertically between a lower inoperative position and one of a plurality of upper operative positions, and permitting it to be fed from one spool to the other at any time during a machine cycle, which is peculiarly adapted for use in an electronic machine and includes means automatically operable to reverse the ribbon feed when the ribbon is completely unwound from either spool. This is accomplished by supporting the ribbon spools and novel feed mechanism on a plastic desk that is pivotally mounted to move the spools and ribbon vertically. with the ribbon feed mechanism comprising a single plastic feed pawl beam having one of two edge notches held by springs in engagement with a laterally oscillatable drive stud. Those springs also tilt the beam to engage one of its ends with a ribbon spool ratchet, whereby lateral sliding of the beam by the drive stud advances that spool to wind the ribbon thereon from the other spool. When such sliding of the feed paw] beam is prevented by ribbon resistance due to all of the ribbon having been unwound from that other spool to which its end is secured, the drive stud automatically moves relative to the beam into engagement with the other edge notch and the springs tilt the beam to engage its other pawl end with the ratchet of the other spool to reverse the direction of the ribbon feeding.

IN THE DRAWINGS FIG. 1 is a top plan view of a preferred embodiment of the invention with the ribbon spools and ribbon shown in broken lines and the feed pawl beam positioned to advance the ribbon from right to left;

FIG. 2 is a plan view like FIG. 1 with the beam set to advance the ribbon from left to right;

FIG. 3 is a detail end elevation, as seen from the right side of FIGS. 1 and 2, showing the different positions of the ribbon and ribbon deck relative to the platen;

FIG. 4 is a detail vertical elevation seen from the front, with parts in section, and illustrating the normal lower or inoperative position of the ribbon deck and spool spindles in full lines and the position of the parts in broken lines when the ribbon is in a first raised operative position;

FIG. 5 is a view similar to FIG. 4 with the lifting link in full lines after selective lateral movement to the left and in broken lines with the ribbon in a second raised operative position; and

FIG. 6 is a detail bottom plan view of the lift cam engaging end of the lifting link, as indicated by the line 66 in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the illustrated embodiment of the invention, reference numeral 11 indicates in general a ribbon deck which is molded as a unitary member from a suitable plastic, preferably poly acrylonitrile-butadiene-styrene (ABS), such as that made by Uniroyal Inc., under their trademark KRALASTIC MM. This deck 1] includes end trunnions 12 extending upwardly from its front corners that are pivotally supported at 13 on rearwardly and upwardly extending arms of an auxiliary frame member 14 in turn secured to a base 15 (shown in FIGS. 4 and 5) which is made as an injection molding from a suitable reinforced phenolic thermo-set molding compound, such as that produced by Fiberite Corporation designated Fiberite 4004. This base 15 is the same as that disclosed and fully illustrated in copending application Ser. No. 366,473, filed June 4, 1973 and which is designated by the same reference numeral 15 therein.

Mounted in suitable apertures in the deck 11 rearwardly adjacent each of the trunnions 12 is a ribbon spool spindle 16 secured in any desired manner to the deck and upstanding therefrom. Rotatably mounted on each spindle 16 is a ribbon spool ratchet l7 molded from a suitable plastic, such as DELRIN, which is provided on its upper surface with integral upstanding lugs I8 (FIGS. 3 and 4) for interlocking cooperation with downwardly extending protuberances 19 on the lower flange of a ribbon spool 2l. The spools 2I are fully illustrated in US. Pat. No. 2,652.9l8, The upper flange of each spool 21 has a latching member 22 (FIG. 3) pivotally mounted thereon with a slot portion slidably engageable in a groove 23 adjacent the upper end of the associated spool spindle 16. Any other suitable means may be employed for retaining a ribbon spool 21 on each of the spindles 16 which will insure rotation thereof with the associated ratchet I7 on the spindle. Each end of a ribbon 24 is secured in the manner described in US. Pat. No. 2,652,918 to the hub or inner bearing portion of one of the spools l6, with the ribbon initially being tightly wound upon one of the spools.

As best seen in FIGS. 1-3, from each of the spools 21 the ribbon 24 extends around a ribbon guide 25 at the rear corner and extending upwardly from the deck 11 which is formed integrally with the latter, the outer surface of these guides 25 being provided with suitable slots 26 for limiting vertical movement of the ribbon relative thereto. In this way, an operable portion of the ribbon 24 is presented between the guides 25 across a platen 27 of any suitable construction for backing paper to receive printing by the printing members (not shown) striking against the ribbon when that operable portion thereof is in a printing area defined by the platen 27. Referring to FIG. 3, the ribbon deck 11 normally is in a lower position, as illustrated therein in full lines, to prevent that operable portion of the ribbon 24 in a lower inoperative position below the printing area referred to, and it may be selectively lifted or swung upwardly about its pivots I3 to either one of a first or second upper operative position. The ribbon comprises an upper half impregnated with one color ink, such as black. and a lower half impregnated with a different color of ink, such as red, so that when the ribbon deck 11 is lifted to the first upper operative position, the upper black portion of the ribbon is presented in operative position in the printing area, and when lifted to the second or highest upper operative position as illustrated in broken lines in FIG. 3, the lower red portion of the ribbon will be moved into operative position in the printing area.

Means normally supporting the rear of the ribbon deck II to dispose the portion of the ribbon 24 between the guides 25 in its lower inoperative position and operable to lift that portion of the ribbon to an upper operative position is best seen in FIGS. 4-6 and comprises an adjustable stud 28 depending from the rear of the deck and a link indicated generally by reference numeral 29 having a pad 3I intermediate its ends on which the lower end of stud 28 rests. The link 29 is pivotally supported at its right end at 32 by the upper end of a lever 33 pivotally mounted at its lower end in any suitable manner on the machine base and, as shown in FIG. 4, normally engaging against an adjustable stop 34 secured to the base 15. The other or free end of link 29 rests upon, and cooperates with, a barrel lifting cam 35 fixed upon, and rotatable by, a shaft 36, as by being press-fitted thereon. That shaft 36 is the same as the takeup reel shaft indicated by reference numeral 18 in Ser. No. 366.473 previously identified, and the lifting cam 35 herein is designated as SI therein. The peripheral surface of cam 35 defines two parallel tracks of different diameters, the smaller or forward one having a substantially horizontal dwell 37, on which the free end of link 29 normally rests, with a rise 37a extending therefrom to its cylindrical outer surface. The track of larger diameter is disposed rearwardly thereof and provided with a notch dwell 38 disposed as shown in FIG. 4 when the cam is in normal at rest position.

Formed integrally with the lifting link 29 is a lateral extension 39 offset rearwardly therefrom having a lower cam surface (FIG. 6) laterally aligned with the larger diameter track of cam 35 and normally spaced outwardly from its dwell 38. Also formed integrally with link 29 is a stud 41 to which one end of a spring 42 is connected, the other end of the spring being anchored by a stud 43 formed on the injection molded plastic base 15. The spring thus comprises means resiliently constraining the free end of link 29 into contact with the lifting cam 35 and the lever 33 into contact with the stop means 34. The cam 35 and the link 29 are each molded from a suitable plastic, such as DELRIN. As seen in FIGS. 4 and 5, the lever 33 pivotally secured to the righthand end oflink 29 has a notch 44 intermediate its ends engaging a pin 45 carried by the plunger 46 of a solenoid 47 which is mounted in any suitable manner on the base 15.

In moving the rear of the ribbon deck 11 in the manner now to be described, an upwardly extending projection 48 from the base 15 cooperates with a slot in a flange 49 depending from the deck as slidably engaging guide means to limit such movements to vertical swinging on the pivots 13. As explained in the copending application Ser. No. 366,473, shaft 36 (shaft 18 in that application) is oscillated through a complete rotation in a counterclockwise direction, as seen from the front of the machine in FIG. 4, and a clockwise return to its normal at rest position during each complete line printing operation. If the line being printed does not require a full translational movement of the printhead (not shown herein) the counterclockwise rotation of shaft 36 may be less than a complete revolution but, in any event, upon completion of its counterclockwise movement, the shaft 36 immediately is returned to its rest position in a clockwise direction. With the ribbon lifting means in their positions illustrated in full lines in FIG. 4, initial counterclockwise rotation of cam 35 through the agency of the rise 37a lifts the free end of link 29 to raise the rear portion of the ribbon deck 11 from its lowermost inoperative position shown in full lines therein and in FIG. 3, to a first upper position illustrated in broken lines in FIG. 4 which disposes the upper or black half of the ribbon 24 in an active position in the printing area. The operative portion of the ribbon between the guides 25 thus is retained in such active position by the smaller diameter cylindrical portion of cam 35 until the printing in that line is completed and the cam 35 returned to its normal at rest position. In the latter portion of that return movement of the cam, spring 42 and the weight of the deck 11 and mechanism carried thereby as supported by the stud 28 insure return movement of the ribbon to its lower inoperative position.

Whenever it is desired to effect printing with the use of the lower half or red portion of the ribbon 24, such as in printing a total, the solenoid 47 is energized in response to a manually operable control key (not shown) which retracts the plunger 46 to move the lever 33 and link 29 from their normal full line positions of FIG. 4

to the left to their full line positions of FIG. 5 without lifting the deck H from its normal inoperative position. Comparing these two Figures will show that such movement of the link 29 to the left has disposed its lateral extension 39 in the dwell 38 of the larger diameter part of cam 35. Consequently, subsequent oscillation of cam 35 will immediately effect lifting of the ribbon deck 11. through the agency of the lower rise surface of notch 38 cooperating with extension 39, to its broken line position of H08. 3 and 5 to dispose the lower or red portion of ribbon 24 in an upper operative position in the printing area. Such positioning of the ribbon will be maintained by the larger diameter cylindrical surface of the cam 35 until the latter is returned to its normal position. at which time the solenoid 47 will automatically be deenergized and spring 42 will return link 29 and lever 33 to their normal full line positions of FIG. 4.

As is also explained in application Ser. No. 366.473. :1 second or power shaft Sl (identified therein by numeral 22) is given one complete revolution during the return or clockwise rotation of the first shaft 36 to rotate a cam 52 (indicated by reference numeral 26 in said application) which is secured to shaft 51 in any desired manner. as being press-fitted thereon. This cam 52 comprises ribbon drive means. having an eccentric peripheral track functioning as a crank arm engaged or embraced by a hooked end of an arm 53 ofa bellcrank 54 pivotally mounted in any suitable manner on the base at 55. An upper arm of the bell crank or feed lever 54 carries a forwardly and horizontally extending drive pin 56 which works in a slot 57 in a flange 58 depending from a power slide 59.

As best seen in FIGS. 1, 2 and 4. the main body of the power slide 59 rests in a laterally extending recess 61 in the upper surface of the ribbon deck 11, with a portion of that recess 6] extending as an aperture through the deck to accommodate the flange 58 depending from the slide. The recess 61 guides and limits lateral movements of slide 59 and the aperture within that recess also enables assembly of the slide into operative position from the bottom of the deck ll. Upward movement of the slide 59 out of its operative position in the recess 61 is prevented by a pair of cross bars 62 extending front-to-rear across it and formed integrally with the deck ll. Upstanding from the power slide 59 and secured thereto in any suitable manner is a drive stud 63 laterally oscillatable with the slide to actuate a feed pawl beam 64 which rests upon the ribbon deck ll and is provided with two notches 65 in its forward edge. one on each side of its center. for cooperation with. and reception of. the drive stud 63. The upper end of stud 63 is flanged to overlie the beam 64, and two coil springs 66 are connected at one end to upstanding studs 67 formed on the beam 64 and at their other ends. respectively. to fingers 68 upstanding from power slide 59 in laterally spaced relation to the drive stud 63 at each side thereof. The springs 66 thus comprise means for resiliently retaining one or the other of the notches 65 in engagement with the drive stud 63 and the pawl end of the beam 64 remote therefrom in engagement with the associated ribbon spool ratchet 17.

As illustrated in FIG. 1. the righthand notch 65 engages the drive stud 63 and the left end of feed pawl beam 64 engages ratchet 17 of the ribbon spool 21 at the left end of the deck 11. Oscillation of feed pawl beam 64 in response to one revolution of power shaft 51 and the cyclically operable feed means 52-59, 63 thus will effect an incremental counterclockwise rotation of the left spool 21 to wind a portion of ribbon 24 onto that spool and off of the righthand spool. as indicated by the arrows in FIG. 1. When successive actuations of the left spool 21 remove all of the ribbon from the right spool. the ribbon 24 will prevent another such oscillation of the feed pawl beam 64 because of the attachment of its right end to the latter. During that attempted oscillation of beam 64 by drive stud 63. the latter will cam itself out of the righthand beam edge notch 65 against the resistance of springs 66 and into the lefthand notch 65 as shown in FIG. 2. As that is accomplished, the springs 66 will tilt the beam 64 to engage its right pawl end with the righthand ratchet 17 to automatically reverse the direction of ribbon feeding for the following oscillations of beam 64 and until similarly again reversed when all of the ribbon is unwound from the left spool 21. In the event that the newly activated end of beam 64 is not fully engaged with its associated ratchet 17, or the drive stud 63 fully seated in the opposite notch 65, the deck 11 is provided with an integrally molded lug 69 (FIGS. 1 and 2) adjacent each ratchet which functions to cammingly engage the activated end of the beam to properly engage it with its ratchet and seat the stud 63 in the new notch 65 during the next oscillation of the ribbon feed means.

It will be appreciated that any desired means may be employed to maintain tension on the ribbon 24, that illustrated herein for such purpose comprising an arm 7! (FIGS. 1 and 2) pivotally mounted on the righthand ribbon spool spindle 16 with an outer end portion urged into engagement with the ribbon by a suitable spring 72. From the foregoing description. it will be seen that the expressed objects of this invention of lifting and feeding a ribbon in a business machine printer have been attained in a unique manner and with maxi mum savings in the costs of manufacturing the parts and assembling the same. In large measure this has been accomplished by eliminating screw-type holding and mounting means and employing molded plastics for a number of the parts. including the ribbon deck 11. auxiliary frame 14, base 15, ratchets l7, link 29, earns 35 and S2, and the feed pawl beam 64. The arms of the auxiliary frame 14, for example. are sufficiently flexible to be spread to accept the pivot pins 13 of the ribbon deck trunnions 12 but are rigid enough to prevent unintentional removal of the ribbon deck, the latter also being guided in its pivotal movements by the base projection 48. And assembly and retention of the feed pawl beam 64 on the deck ll is accomplished simply by inserting the power slide 59 upwardly into the deck recess 61 and below the cross bars 62. laying the beam 64 thereover with one of the edge notches 65 engaging the drive stud 63 under its flanged head, and interconnecting the springs 66 between the studs 67 and fingers 68.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description. and it will be apparent that various changes may be made in the form. construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim: 1. In a business machine printer having a printing area defined by a platen for backing paper to receive line printing, horizontal pivot means spaced forwardly from said platen, a ribbon deck pivotally supported at its front by said horizontal pivot means and having a ribbon guide at its rear adjacent each end of said platen, a ribbon spool spindle upstanding from said deck adjacent each ribbon guide, a ribbon, a spool con nected to each end of said ribbon and rotatable on a said spindle, cyclically operable feed means for winding the ribbon from one of said spools across said guide to the other of said spools, and means normally supporting the rear of said deck to present a portion of said ribbon extending between said ribbon guides in a lower inoperative position and selectively operable to lift said portion of said ribbon to first or second upper operative positions and maintain the same therein during printing of each line, wherein said last recited means for supporting the rear of said deck comprises a cyclically operable lifting cam, and a link having a first end engaging said cam, a second pivotally mounted end and a connection intermediate said ends with said deck, whereby said cam raises said free end of said link to lift the rear of said deck to maintain said ribbon in an upper operative position during the printing portion of a machine cycle.

2. A business machine printer according to claim 1, wherein said cam and said link comprise molded plastic parts.

3. In a business machine printer according to claim I, a lever connected to said second end of said link, said cam having one part normally supporting said first end and a normally inoperative second part, and means selectively operable to actuate said lever to swing the same from normal position to move said link relative to said lifting cam to engage said first end with said second part, whereby said cam lifts the rear of said deck to maintain said ribbon in a second upper operative position during the printing portion of a machine cycle.

4. A business machine printer according to claim 3, wherein the peripheral surface of said lifting cam defines said parts and comprises parallel tracks of different diameters each having a dwell, with the free end of said link normally resting upon the dwell in the smaller diameter said track, and a lateral extension on said link movable into operative association with the dwell in the larger diameter said track in response to actuation of said lever.

5. In a business machine printer according to claim 4, stop means cooperating with said lever to determine its normal position, and means connected to said link resiliently constraining the free end of the latter into with said stop means.

6. A business machine printer according to claim 5, wherein said selectively operable means comprises a solenoid having a plunger connected to said lever.

7. A business machine printer according to claim I, wherein said ribbon deck and said ribbon guides are formed as a unitary molded plastic part.

8. A business machine printer according to claim 2, wherein each said spool is drivingly connected to a ratchet, and said feed means comprises said ratchets, a laterally oscillatable drive stud supported by said deck, a feed pawl beam having two edge notches intermediate its ends with each end associated with a said ratchet, and spring means for resiliently retaining one or the other of said notches in engagement with said drive stud and the end of said beam remote therefrom in engagement with its associated said ratchet, wherein the ends of said ribbon are secured, respectively, to said spools, whereby lateral movement of said feed pawl beam by said drive stud is prevented by said ribbon when it is completely unwound from one of said spools and said drive stud resultingly moves from engagement with one into engagement with the other said edge notch to automatically reverse the direction of ribbon feeding by subsequent oscillation of said feed means.

9. In a business machine printer according to claim 8, means cooperating with the active end of said feed pawl beam to insure proper engagement thereof with the associated said ratchet and of said drive stud with said other edge notch.

10. A business machine printer according to claim 8, wherein said feed pawl beam and said ratchet comprise molded plastic parts.

11. A business machine printer according to claim 8, wherein said ribbon deck is provided with a laterally extending recess in its upper surface, and a power slide slidably mounted on said deck, connected to said drive stud for oscillating the same and disposed in said recess, whereby the latter guides movements of said slide.

l2. In a business machine printer according to claim 11, wherein a portion of said recess extends through said deck and a depending part of said power slide extends therethrough, a feed lever pivotally connected to said depending part, and a ribbon feed cam cyclically operable to oscillate said feed lever and said power slide. 

1. In a business machine printer having a printing area defined by a platen for backing paper to receive line printing, horizontal pivot means spaced forwardly from said platen, a ribbon deck pivotally supported at its front by said horizontal pivot means and having a ribbon guide at its rear adjacent each end of said platen, a ribbon spool spindle upstanding from said deck adjacent each ribbon guide, a ribbon, a spool connected to each end of said ribbon and rotatable on a said spindle, cyclically operable feed means for winding the ribbon from one of said spools across said guide to the other of said spools, and means normally supporting the rear of said deck to present a portion of said ribbon extending between said ribbon guides in a lower inoperative position and selectively operable to lift said portion of said ribbon to first or second upper operative positions and maintain the same therein during printing of each line, wherein said last recited means for supporting the rear of said deck comprises a cyclically operable lifting cam, and a link having a first end engaging said cam, a second pivotally mounted end and a connection intermediate said ends with said deck, whereby said cam raises said free end of said link to lift the rear of said deck to maintain said ribbon in an upper operative position during the printing portion of a machine cycle.
 2. A business machine printer according to claim 1, wherein said cam and said link comprise molded plastic parts.
 3. In a business machine printer according to claim 1, a lever connected to said second end of said link, said cam having one part normally supporting said first end and a normally inoperative second part, and means selectively operable to actuate said lever to swing the same from normal position to move said link relative to said lifting cam to engage said first end with said second part, whereby said cam lifts the rear of said deck to maintain said ribbon in a second upper operative position during the printing portion of a machine cycle.
 4. A business machine printer according to claim 3, wherein the peripheral surface of said lifting cam defines said parts and comprises parallel tracks of different diameters each having a dwell, with the free end of said link normally resting upon the dwell in the smaller diameter said track, and a lateral extension on said link movable into operative association with the dwell in the larger diameter said track in response to actuation of said lever.
 5. In a business machine printer according to claim 4, stop means cooperating with said lever to determine its normal position, and means connected to said link resiliently constraining the free end of the latter into contact with said lifting cam and said lever into contact with said stop means.
 6. A business machine printer according to claim 5, wherein said selectively operable means comprises a solenoid having a plunger connected to said lever.
 7. A business machine printer according to claim 1, wherein said ribbon deck and said ribbon guides are formed as a unitary molded plastic part.
 8. A business machine printer according to claim 2, wherein each said spool is drivingly connected to a ratchet, and said feed means comprises said ratchets, a laterally oscillatable drive stud supported by said deck, a feed pawl beam having two edge notches intermediate its ends with each end associated with a said ratchet, and spring means for resiliently retaining one or the other of said notches in engagement with said drive stud and the end of said beam remote therefrom in engagement with its associated said ratchet, wherein the ends of said ribbon are secured, respectively, to said spools, whereby lateral movement of said feed pawl beam by said drive stud is prevented by said ribbon when it is completely unwound from one of said spools and said drive stud resultingly moves from engagement with one into engagement with the other said edge notch to automatically reverse the direction of ribbon feeding by subsequent oscillation of said feed means.
 9. In a business machine printer according to claim 8, means cooperating with the active end of said feed pawl beam to insure proper engagement thereof with the associated said ratchet and of said drive stud with said other edge notch.
 10. A business machine printer according to claim 8, wherein said feed pawl beam and said ratchet comprise molded plastic parts.
 11. A business machine printer according to claim 8, wherein said ribbon deck is provided with a laterally extending recess in its upper surface, and a power slide slidably mounted on said deck, connected to said drive stud for oscillating the same and disposed in said recess, whereby the latter guides movements of said slide.
 12. In a business machine printer according to claim 11, wherein a portion of said recess extends through said deck and a depending part of said power slide extends therethrough, a feed lever pivotally connected to said depending part, and a ribbon feed cam cyclically operable to oscillate said feed lever and said power slide.
 13. In a business machine printer according to claim 11, wherein said spring means comprises a pair of springs connected at one end to said feed pawl beam, a finger extending upwardly from said power slide in laterally spaced relation to said drive stud at each side thereof and connected, respectively, to the other ends of said springs. 